Controller



Jan. 16, 1940. J. T. NICHOLS CONTROLLER Original Filed July 17, 1935 IFfVFES/A/fi MOTOR lnvenfor:

Joy/v T. N/CHOLS,

Patented Jan. 16, 1940 UNITED STATES PATENT OFFICE CONTROLLER Pennsylvania Application July 17, 1933, Serial No. 680,886 Renewed June 17, 1939 9 Claims. Tlii'sinvention is a controller adapted for use wherever conditions are such that a variable light is produced. For instance, it may be used to control any furnace which operates at sufficiently 5 high temperatures to produce light, or wherever the operation of 'a photometric pyrometer is possible.

Fundamentally, the invention embodies the ombination of a furnace having a heat control, a

photoelectric unit arranged to receive light from the interior of this furnace, another photoelectric unit, some means for illuminating this other unit and a means controlled by the relative conductivities of these two units for operating the furnaces heat control.

The illuminating means More specifically, the two photoelectric units are. arranged to produce an electrically balanced ircuit, and the illuminating means may be an electric lamp energized by a constant current source. tween. it

This lamp may have a diaphragm beand the secondly mentioned unit, which provides an opening of adjustable. proportions so that the light received'by this unit may be varied,

and, in addition, a small resistance may be placed in series with this lamp and controlled by the operation of the furnaces heat control.

The

means for operating this heat control may then becontrolled by the balanced or unbalanced conspecific example of the invention.

ition of the circuit as produced by the two photolectric units.

The accompanying diagram illustrates a The two photoelectric units l and 2 are connected in series by a line 3 and to batteries 4 and 5, also connectedin series, by lines 6. The unit I is enclosed by a casing 1 and receives its light through a lens 'andscreen 9, it being understood that this light is that which is to be measured or, in other words, the light which comes from the interior of a furnace A. Theunit 2 is provided with an illuminating lamp [0 whose light must pass through a screen H and an iris diaphragm I2, the latter being controlled by a ring l3 through the usual mechanism. These elements are shielded against extraneous light by a casing 14. This lamp is, in effect, a variable illuminating means.

A three-element vacuum tube-- l5-has its anode onnected to the positiveside of the battery 4 through a battery It in series therewith. The tubes grid is connected to the line 3 between the two units by a line IT, and its cathode is connected between the batteries 4' and 5 by a line I 8.

A galvanometer relay i9 is connected in series with the line I8 50 that it is operated by the output of the tube l5. This galvanometer relay includes a movable contactor 2i] and two fixed contacts 2| and 22, and has a weighted movement which causes it to operate at a current value corresponding to the sensitive portion of the tubes characteristics. Thus this relay is balanced so that its contact 29 is free from its fixed contacts 2i and 22 when the two units I and 2 have equal conductivities. In other words, this relay I9 is a switching means controlled by the current between the units l and 2 and the current sources 4 and 5, or is a switching means controlled by the relative conductivities of these two units.

A battery 23 is connected to the lamp Iil by lines 24 through a small variable resistance 25. Assuming the resistance 25 to be set so that the lamp ill produces a light having a constant value and that the diaphragm I2 is set to pass a certain amount of this light, it is apparent that the relay !9 will operate whenever the conductivity of the unit l varies from that of the unit 2. Ther fore, by adjusting these variables so that the unit 2 is illuminated the same as the unit i when the furnace A is at a determined temperature, the galvanometer relay l9 operates whenever the temperature of the furnace A varies from this determined value. Obviously, the contacts 29, 2| and 22 may be used to control the furnaces temperature by the use of suitable apparatus.

In the present instance, the furnace A is heated by a resistance 26 which is powered by lines 21 through a variable resistance 28, the latter constituting the furnaces heat control. The movable contactor 28 of the resistance 28 is operated by a reversing motor 29 through a shaft 30, this motor also driving a second shaft 30 which moves the movable contactor 2.5 of the resistance 25, the latter being'that controlling the current to the lamp I0.

The motor 29 is connected to the lines 21 by lines 31" and is controlled by'the contacts of the galvanometer relay l9 through a relay 32. Thus, the motor 28 Will operate in one direction or another, under the control of the galvanometer relay I9 which is, in turn, controlled by the currentbetween the units l and 2. The furnace control isnot more particularly described because of its many variations. For instance, the furnace A may be fired by gaseous fluid, in which case the motor 2Q may control damper or valve systems.

In operation, the diaphragm I2 is adjusted by its ring it to pass a proper quantity of light, this ring being preferably provided with marks suitably calibrated in temperature readings. Other forms of light valves may be used. When the furnace A is at the thusly determined temperature, the units l and 2 will have equal conductivities and the contact will be free from its fixed contacts. The screens 9 and H may be colored to pass monochromatic red light so as to render any black body corrections of little consequence. Also, the screens may be shaded differently to correct the units 8 and 2, should the latter have different characteristics.

If the temperature in the furnace A should decrease, the conductivity of the unit I becomes less than that of the unit 2, the grid of the tube l5 becomes negative and the current through the relay i9 decreases. This causes the contact 20 to close with one or another of its fixed contacts and effect operation of the motor 29 in a direction which removes some of the resistance 28.

Simultaneously, some of the resistance is removed from the lamp l0 so that the illumination of the unit 2 is slightly increased, this preventing drifting of the system as a whole. If the temperhigher so that the I ature of the furnace becomes unit l is illuminated more brightly than the unit 2, the reverse of the foregoing occurs. It is assumed'throughout that the contacts 20, 2| and 22, the relay 32 and the control leads of the motor 29 are suitably associated to produce the operations described. The association may be effected by any electrician.

The effect of the adjustment of resistor 25 is such as to raise the control point, or normal temperature which the system tends to maintain, in response to a decrease in furnace temperature and to lower the control point on an increase in that temperature with the net result that the tendency will be for a charge being heated in said furnace to be maintained at a constant temperature notwithstanding changes in furnace load.

Although a specific form of this invention has been shown and described in accordance with the patent statutes, it is not intended to limit the scope of the invention exactly thereto, except as defined by the following claims.

I claim:

1. The combination of a furnace having a heat control, a photoelectric unit arranged to receive light from the interior of said furnace, a second photoelectric unit, variable illuminating means for said second unit, means controlled by the relative conductivities of said units for operating said heat control and means for varying said illuminating means proportionately tothe operation of said heat control.

2. The combination of a furnace having a heat control, a photoelectric unit arranged to receive light from the interior of said furnace, a second photoelectric unit, means for illuminating said second unit so that its conductivity is the same as the first named unit when said furnace is at a determined temperature, means controlled by the relative conductivities of said units for operating said heat control and means for slightly varying the illumination of said second unit proportionately to the operation of said heat control.

3. The combination of a furnace having a heat control, at least two photoelectric units connected in series, one of said units being arranged to receive light from the interior of said furnace and the other being provided with a variable illuminating means, a plurality of current sources connected in series to energize said units, switching means controlled by the current between said units and their current sources, means controlled by said switching means for operating said heat control, means for manually varying said illuminating means and automatic means for slightly varying said illuminating means proportionately to the operation of said heat control.

l. The combination of a furnace having a heat control, at least two photoelectric units connected in series, one of said units being arranged to receive light from the interior of said furnace and the other being provided with an illuminating lamp, a plurality of current sources arranged in series to energize said units, a grid controlled electronic tube having its grid controlled by the current between said units and their current sources, a relay switching system controlled by the output of said tube, and a reversing motor controlled by said system and operatively connected to said heat control.

5. The combination of a furnace having a heat control, at least two photoelectric units connected in series, one of said units being arranged to receive light from the interior of said furnace and the other being provided with an illuminating lamp, a plurality of current sources arranged in series to energize said units, a grid controlled electronic tube having its grid controlled by the current between said units and their current sources, a relay switching system controlled by the output of said tube, and a reversing motor controlled by said system and operatively connected to said heat control, said lamp having a current source connected thereto and a variable resistance in series therewith, the latter being operatively connected to said motor.

6. The combination of a furnace having a heat control, at least two photoelectric units connected in series, one of said units being arranged to re-.

ceive light from the interior of said furnace and the other being provided with an illuminating lamp, a plurality of current sources arranged in series to energize said units, a grid controlled electronic tube having its grid controlled by the current between said units and their current sources, a relay switching system controlled by the output of said tube, and a reversing motor controlled by said system and operatively connected to said heat control, said lamp having a maually adjustable light valve between it and the second named unit.

'7. The combination of a furnace having a heat control, at least two photoelectric unitsconnected in series, one of said units being arranged to receive light from the interior of said furnace and the other being provided with an illuminating lamp, a plurality of current sources arranged in series. to energize said units, a grid controlled electronic tube having its grid controlled by the current between said units and their current sources, a relay switching system controlled by the output of said tube, and a reversing motor controlled by said system and operatively connected to said heat control, said lamp having a current source connected thereto and a variable resistance in series therewith, the latter being.

operatively connected to said motor, said lamp also having a manually adjustable lightvalve between it and the second named unit.

3. The combination of a furnace having a heat 75- 1 the other being provided with an illuminating means, a plurality of current sources connected in series to energize said units, a grid controlled electronic tube having its grid controlled by the current between said units and their current sources, a galvanometer relay connected for operation by the output of said tube and constructed to operate at a current value corresponding to the sensitive portion of said tubes characteristics, and means controlled by said relay for operating said heat control.

JOHN T. NICHOLS. 

